How To Hunt For Life As We Don’t Know It

IRA FLATOW: This is Science Friday. I’m Ira Flatow. We have learned that water can be found in many places in our solar system, of course, not just on Earth. And with each of these discoveries of water, on Mars, Europa, Enceladus, the likelihood increases of some kind of life existing out there, too. You know the old saying, if there’s water, there might be life.

But how do you plan a mission to look for that if you don’t know what it might look like? I mean, it might not be like the kind of life you and I are used to here. Well, for the rest of the hour we’re going to hope to find out. We’re going to be talking astrobiology. That’s what they call the search for life in outer space there, astrobiology. And how environments on our own Earth could serve as a useful analog for searching for life on distant worlds.

And if you want to join our conversation, please give us a call, doesn’t matter which part of the universe you live in. 844-724-8255, that’s 844-SCI-TALK, or tweet us @scifri. So if you’re calling from Saturn don’t reverse the charges on this one. Let me introduce, first up, my guest joining me now is someone who’s been out to one of the labs that is planning for missions to some of those icy worlds. Our own Chau Tu, who has written an article on our website at sciencefriday.com. You can read her article, and there’s a video about the lab that she visited on our website at sciencefriday.com. Welcome, Chau.

CHAU TU: Hi, Ira.

IRA FLATOW: So you went out to watch where they were– what are they doing? They’re trying to recreate the icy world of these moons?

CHAU TU: Yeah. So there’s this smallish lab at JPL, the Jet Propulsion Laboratory in Pasadena, California, and they are focused, they’re called the icy world simulation lab. So they’re focused on simulating the surface of icy worlds in, mostly, our outer solar system. And I like to call it kind of an idea lab, because they’re essentially coming up with creative sort of MacGyver-like experiments to make these simulations. It was really fascinating to visit.

IRA FLATOW: What do you mean MacGyver? I saw that they sort of jerry-rigged their original project together.

CHAU TU: Yeah.

IRA FLATOW: Tell me what that was like, what did they do?

CHAU TU: Yeah, so one of the experiments that I saw them working on, it was this stockpot, basically, something that you can make gumbo in. And they had sort of a foam that was duct taped to the outside and they put liquid nitrogen in there. And that was kind of them growing ice. They were sort of trying to simulate what the ice on Europa is like and trying to figure out what the surface is like.

IRA FLATOW: So why is Europa a good choice for trying?

CHAU TU: So Europa is a big focus for NASA and JPL right now, most because we believe that there could be an Earth-like ocean underneath its ice shelf. So there is a mission planned for around 2022 to launch a spacecraft that would do multiple flybys of the moon, so we can get a better look to see about what’s going on there.

IRA FLATOW: Yeah, looking at the video, also we have a video up on our website about this, the ice is very thick. Europa’s about, what, 20 kilometers or something like that?

CHAU TU: Yeah, I think the ice shelf’s supposed to be about 20 kilometers, and they think the ocean underneath it would be about 100 kilometers.

IRA FLATOW: Wow.

CHAU TU: Still pretty big in comparison to Earth’s ocean, but yeah.

IRA FLATOW: Yeah, and what we learn from Earth’s ocean is that you don’t have to have light, because the light is not going to get below that ice level, right?

CHAU TU: Right.

IRA FLATOW: You don’t have to have light for life. We have these– at the bottom of the oceans on Earth there is no light but we have sources of heat, right, that come up and support life that never sees light.

CHAU TU: Right, right, so just a lot of what they’re trying to study right now is how we might be able to further land on the surface and study it and then figure out what’s underneath.

IRA FLATOW: Wow. So Let’s talk about the lab you visited. How big a chunk of ice of an icy world– I mean, you said they started out with a stockpot.

CHAU TU: Yeah.

IRA FLATOW: Did they keep it a stockpot? Were they able to go a little more expensive?

CHAU TU: Yes, so they’ve graduated now to another sort of experiment. It’s a lot fancier, I guess you can say. They’ve dubbed it the Ark of Europa, kind of after the Indiana Jones ark. But it’s now this kind of vacuum-sealed stainless steel chamber. And inside there they are still growing ice, sort of simulating that sort of environment. And yeah, they’re just becoming a little bit more– they can sort of make sure that all their measurements are more accurate working with that.

IRA FLATOW: Now, and I saw from the pictures on our website, the ice doesn’t look like the kind of ice you think– you’re walking on your driveway. It comes in all shapes and different forms.

CHAU TU: Right, so again, we don’t really know what Europa’s surface is like. So that’s what they’re trying to do, is they’re trying to see what might grow there. There’s an idea, there’s a theory that there’s these things called penitentes that might form on Europa, and these are actually rather common on Earth, here, in the Andes Mountains. And they are kind of like big ice stalagmites, so just like huge upside down icicles coming from the ground. So they’re trying to see if they can grow these, because if they do grow on Europa, that would kind of change how we would build a lander, know how to land on the surface of Europa, or even how to scan the surface using a radar.

IRA FLATOW: You know, it reminded me when we were thinking about going to the moon, originally, back in the Apollo days, people thought, you might be able to sink. You might sink in, it might be just a bunch of dust there. And if you land on there you’re going to sink right through. Because we had never been there and we have never been to these planets. We haven’t been to the moons of these planets. So we don’t know what kind of ice we might find there, and if we don’t know– if we send some sort of robot, we don’t want it to fall into the ice.

CHAU TU: Exactly, yeah. If these stalagmites or upside down icicles are there, it’s not exactly flat, so we wouldn’t be able to send a normal type of spacecraft.

IRA FLATOW: Mm-hmm. Do they have their ideas, or what’s the goal– let me go back to the most basic information here. Will any mission actually change based on what they find in the lab, or how will they recreate as close as possible to what these moons are like?

CHAU TU: Yeah, so a lot of the work that they’re doing is sort of informing about the types of tools and the types of spacecraft that we might be able to send there. So right now there’s a mission plan do flybys. There’s not a mission plan for a lander quite yet, but it’s very possible, and they want to be prepared for that, for any sort of scenario.

IRA FLATOW: Well, thank you, Chau, to help us flesh this out a little more. We are going to bring a mission scientist in. Before we go, I want to thank you, speaking for a staff, I know that this is your last–

CHAU TU: It is.

IRA FLATOW: We’re bidding you a fond farewell. You’re going to be moving on.

CHAU TU: I am going to be moving on, but my heart will always be with Science Friday.

IRA FLATOW: Well, take a little bit of our heart with you. We want to thank you for all your hard work and good cheer.

CHAU TU: Thank you, Ira. That’s very sweet.

IRA FLATOW: And good luck to you.

CHAU TU: Thank you.

IRA FLATOW: Mary Voytek is the senior scientist in astrobiology at NASA’s science mission directorate, and she is based at NASA HQ, as they say, in Washington. Welcome to Science Friday.

MARY VOYTEK: Hi, Ira. I’m glad to be here.

IRA FLATOW: It’s glad that we could get you on here. Tell us about the missions to these. Why are these moons chosen? Why do we think that’s the best place to possibly find life?

MARY VOYTEK: Well, Ira, as you know, it’s been NASA’s focus as a fundamental requirement of life to look for environments that have water. That’s pretty key. And of the moons that we know anything about around Saturn and Jupiter, there’s an estimate of them having about 30 times the amount of water that we see on Earth, if you combine them all together. So that seems like a very rich place to go to look for life that requires water.

IRA FLATOW: And how confident are you that that life elsewhere in the solar system will have a chemistry of our own? I mean, we were talking at the beginning about how do you look for a life that may not be recognizable easily, here on Earth?

MARY VOYTEK: You’ve come to the crux of the problem in searching for life. A lot of our studies certainly began with understanding as much as we could about what life we have here on Earth and fully appreciating its diversity. It was really important to decide what sorts of crooks and niches that inhabits here on Earth, and as a result, we realized that there is a huge diversity of places that you can find life, although the solution to it. In terms of chemistry and acquiring energy is diverse, it’s still pretty fundamentally similar in most all organisms on Earth.

So when you go to look for life elsewhere, you can certainly prepare yourself by understanding as much as you can about the one sample example that we have, but we can also start trying to think more about biology or life more universally. What sort of things can we imagine they might need? We know that they’d have to have energy. We know that it turns out that life leaves its mark on planets and environments as it uses the resources that it needs to make cells to gain energy.

And so we’ve sort of shifted a little bit just to start thinking more broadly about what would those signs of, or evidence of life be, if we didn’t know exactly what it looked like or what chemistry was doing. Could we look for unexplainable aspects of chemistry that we would measure, that can only happen if there is something like life working on it? And so it’s a difficult problem, but we are trying to think about it, to get the best value out of the missions when we go looking for life.

IRA FLATOW: So are you saying that you’re looking for residues that life would leave behind, without actually having to identify what the life is?

MARY VOYTEK: Well, we plan on having, first of all, we have learned that you don’t just rely on one thing. And so we’re going to look for the things that would be obvious. If we knew it was exactly like Earth life, what tools would you use, and would you select, what measurements would you make to identify Earth-like life somewhere else? And then we’re trying to also see if those instruments can also look more broadly and look for changes in environments in terms of its chemistry, for example, that would indicate that life was present.

Let me give you an example. We know that life begins with using carbon, and uses it in many forms. Structurally, for energy, for basic machinery, and in doing so some of the pieces that it uses are quite simple, but ultimately, some of the molecules that it makes to function in the cell are very complex. And so just generically, we might expect that if you saw a suite of organic compounds, that if they were all very simple, we know that those can be made without biology, but if they’re very complex with lots of innovations in terms of their structure, that that would possibly be a sign of evidence for life having acted and produced those particular molecules.

IRA FLATOW: We have a lot of people asking one simple question, and so many of us have watched Star Trek and other science fiction movies. We’re up. I’m going to go to the phones and let Renee in Cleveland ask the question. Hi, Renee.

RENEE: Hi, Ira. Thank you so much for taking my call. I was wondering, is assuming that life is carbon-based or that it would be making complex carbon molecules, is that just extrapolating from what we know about life on Earth? Is that showing any kind of lack of imagination in terms of what other living organisms could be capable of? Or are we pretty much determined that it’s carbon all the way?

IRA FLATOW: Let me just first say this is Science Friday from PRI, Public Radio International. And Dr. Voytek, she reflects about half a dozen tweets that have come in, also saying, could it not be carbon-based? What if it’s something else? Would we recognize it?

MARY VOYTEK: Well, I think certainly any instruments that we sent up that were based on carbon would miss that signal. And we’re very worried about what we call false negatives. We don’t want to miss it. On the other– and so some of the things that we’re looking for is potentially, like I mentioned before, an usual usage of materials that we could imagine could be used. Carbon is something that we focus on because, of course, here on life, it’s used for everything in the cell. And many of the functions that go on in the cell, our scientists have found difficult to imagine as an efficient and useful element as carbon.

And so it’s not that we don’t think about that. We’re always going– silicon is the obvious thing as there are hordes out there. But we don’t– and if there was, I mean, we are also sending instruments that are looking at mineralogy. So we would pick up things like silicon. And we might be able see from the pattern of its usage or the distribution of a sample that this would be consistent with there potentially being a life form. It would be much harder for us to confirm that, since we would know so little about that, but we would start getting clues that that might be something we need to pursue further.

But you guys have asked, as I mentioned, the most important question or troubling question or challenge for us is, how do we look for what we don’t know? And if it’s there and we’re not looking, are we going to see it? So it’s truly a challenge.

IRA FLATOW: We have a shout-out from Bob [INAUDIBLE] who is listening, and says, excited and fortunate to work with these wonderful people exploring strange icy worlds, NASA Europa. He tweeted that in today. So we want to shout out to him, [INAUDIBLE].

Let’s go to see if I can get another phone call in. Let’s go to Greg in Sacramento. Hi, Greg.

GREG: Hi, Ira, great show, love your work, man. This is a question for your guest. Is there like a Star Trek prime directive? If you do find life, at what point do you break off and say it’s better that we leave it alone? If you do find life. Just curious. I’ll take my answer offline.

IRA FLATOW: Thanks. Is there a directive?

MARY VOYTEK: Well, we have something called planetary protection that’s, in its grossest sense, let’s say, pays attention to making sure that we don’t take contaminants of any sort to another planet that might potentially interfere with life going on there. And we also worry about bringing anything back. I think it is a goal of ours to find it. We want to find it in situ if we can. We want to find it in samples that we bring back. And I think that we want to do it not at the expense of the actual organisms or population. That’s how we sample things on our planet in general. We want to understand it, but we certainly wouldn’t want to eradicate it or interfere to any great extent with its thriving.

IRA FLATOW: Sounds exciting. Can’t wait for that probe, which is a few years away, I’m sure, before it takes off. Mary Voytek, senior scientist in astrobiology, NASA’s science mission directorate at NASA headquarters in Washington. Thank you. Thanks for taking time to be with us today.

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